In the manufacture of multistage venturi ejectors, it is common to provide several ejector body portions, each with different sizes and shapes of air passages, which are assembled to form a multi-stage unit. A first or upstream unit has a venturi and a mixing nozzle, and the downstream units have mixing nozzles, each of which is usually a separately manufactured unit assembled into the ejector body. The manufacture of such units requires extensive machining and accurate assembly operations, which unduly increases the cost of the final product.